Rider for brush on commutator



Se t. 4, 1962 J. DE RUGERXS 3,052,764

RIDER FOR BRUSH 0N COMMUTATOR Filed Dec. 21, 1959 INVENTOR. JOHN D RUGL-YP/S H/S A 7' TORNEVS United States Patent 3,052,764 RIDER FOR BRUSBH ON COMMUTATOR John De Rugeris, 527 Kenneth Ave., Campbell, Calif. Filed Dec. 21, 1959, Ser. No. 860,817 4 Claims. 01. 200-23 This invention relates to ignition systems for internal combustion engines and more particularly to an improved form of commutator and rider in the make and break arrangement of such systems by which the current of the primary side of an induction coil is controlled.

The present invention is embodied in a make and break arrangement which will give a long period of current build-up to the primary winding of the coil in the ignition system. More particularly the present invention contemplates the provision of a brush and commutator arrangement in which no cam action is required. Reference may be had to my co-pending application Serial No. 769,470, filed October 24, 1958, now Patent No. 3,004,- 115, and dated October 10, 1961, showing one form of brush and commutator arrangement suited for such operation.

In general the present invention finds its environment in combination with a commutator having a plurality of nonconductive zones provided by gaps between conductive lands. The brush for such an arrangement must have a thickness less than the width of each gap and this requires means between the brush and commutator for supporting the brush peripherally of the commutator at all times.

commutator type make and break arrangements for the ignition system of internal combustion engines are shown in the patents to Callander No. 2,510,067, dated June 6, 1950; Jernigan No. 2,730,582, dated January 10, 1956; and Robertson No. 2,830,140, dated April 8, 1958. Each of these prior devices contemplate a make and break arrangement which will give a long period of current build-up to the primary winding of the coil. Robertson in particular contemplates the provision of such an arrangement in which the break is sudden so as to enable the discharge of the current from the primary winding at the peak of its charge.

This application is a continuation in part of my United States application Serial No. 769,470, filed October 24, 1958, in which a commutator body of conductive material having its periphery divided into a plurality of conductive lands separated by gaps is embraced by nonconductive brush supporting tracks for the purpose of supporting a brush narrower than the gaps peripherally of the commutator.

The present invention contemplates the provision of another form of brush support in combination with a commutator having gaps between conductive lands. In this connection an electrically non-conductive rider secured to the brush rides the conductive lands as the brush which is narrower than the gaps passes any one These and other objects and advantages of the present invention will become apparent in the following description when read in the light of the drawings in which:

FIG. 1 is a side elevation of a distributor mounted on an engine block which is fragmentarily shown.

FIG. 2 is an enlarged plan view of P16. 1 with the distributor cap thereof removed, this view being taken along line 22 of FIG. 1 to show a plan view of the make and break arrangement embodied in the present invention.

1 1G. 3 is a perspective view of the commutator of the present invention mounted on the distributor shaft which is shown fragmentarily.

MG. 4 is a horizontal section through FIG. 3.

FIG. 5 is a schematic wiring diagram of an ignition system embodying the commutator of the present invention in a make and break arrangement.

The distributor 16 shown in FlG. 1 is of conventional design except insofar as it is conditioned for use with a make and break arrangement embodying the commutator of the present invention. Suffice it to say that the distributor 10 has a housing 11 through which a shaft 12 extends, which shaft 12 is drivingly connected in the customary manner to the drive or crank shaft of the internal combustion engine E so as to turn in timed relation therewith, usually at half speed with respect thereto.

The upper end 13 of shaft 12 is configurated for keyed connection to a rotor arm 14, the outer end of which makes contact with several conductive lands 15 embedded in a distributor cap 16 in conventional manner and having connection by wires :17 to the respective spark plugs (not shown) of the internal combustion engine E with which the distributor is operatively associated. The rotor arm 14 is also connected by a wire 18 to one side of the high voltage or secondary winding 19 of a coil 21?, the opposite side or primary winding 21 of which is connected to one lead of a triode type transistor 22 the opposite lead of which receives current from a battery B.

The make and break arrangement in which the present invention is embodied is shown at 25 in FIG. 2 which depicts a chamber 26 confined within a wall 26' of the distributor housing 11 and accessible for repairs when the cap 16 is removed from the housing 11. The make and break arrangement 25 consists of a commutator 27 secured to the distributor shaft 12 for rotation therewith and a brush 2S normally urged toward the commutator for continuous surface contact therewith. The brush 28 is secured to one end of an arm 29 having its other end pivotally mounted on a stud pin 30 standing up from the floor of chamber 26 and having the usual coil spring arrangement for urging the arm 29 toward the center of the chamber 26.

The brush 28 is connected by a flexible wire 31 to the internal end of a binding post 32 extending through the wall 26' of the distributor housing 11. The opposite end of the bin-ding post 32 is grounded via a condenser C and by wire 31 is connected to the third lead of the triode transistor 22. Although I have shown the source of electrical energy as a storage battery B in the present disclosure it could well be a magneto if desired.

The battery B has its other terminal grounded to the engine block E. In accordance with the present invention the commutator 27 is also grounded to the block E so as to complete the foregoing low voltage circuit between the battery B and the brush and commutator. To etfect grotmding of the commutator 27, the ground brush 35 is embodied in the distributor housing 11 which is secured to block E as best seen at the cut away section in FIG. 1. This ground brush 35 is urged radial-1y toward the shaft 12 by a spring 36 which is backed by a screw plug 37 threaded into a bore 38 provided in the housing 11.

It is appreciated that a commutator and brush arrangement is not broadly new and I am aware of the fact that others have attempted to use this type of arrangement in ignition systems before. In every case of such use of which I am aware, little or no success has been achieved mainly because of failure to understand the function and operation of the current build-up in the primary winding 21 of the induction coil 20. Experiments with prior known commutators and brushes have established the fact that they have been unsatisfactory because the actual contact between the brush and the conductive areas of the commutator have been of so short a duration that insufficient build-up of current is afforded the primary winding 21. Moreover, the brush, although touching the conductive areas of the commutator, has been allowed to bridge or maintain some contact with the non-conductive area of the commutator with the result that leakage or gradual current drop occurred before, and during the gap or discharge period. In other words, it is now well established that it is only when a complete and sudden break of contact occurs that the current built up in the primary winding of the coil can be discharged with its fullest impact. Consequently, in the embodiment of the present invention there must be a direct relationship between the surface area of the brush 28 with respect to the area of the non-conductive zones when the break occurs after each current build-up received from a conductive land.

In FIG. 2 I have shown the commutator 27 as consisting of a solid body 4% of conductive material. This body 40 is press fit upon the distributor shaft 12 to assure electrical conductive as well as rotary movement of the body 40 with the shaft 12. The body 40 is round and concentric to shaft 12 so as to present the periphery 41 of body 40 to the brush 28 for surface contact therewith.

In accordance with the present invention, non-conductive zones 42 are provided in the body 40 by forming gaps or recesses 43 therein opening up onto the periphery of the body 4t). In FIG. 4 the recesses 4-3 are formed in the body 46 in radial array on a common radius and at angular disposition relative to each other, there being one such recess 43 for each cylinder of the engine E with which the commutator 27 is to be associated.

In the construction of this form of commutator the body 4t) is milled out to form kerf-like recesses 4-5 at proper locations radially from the periphery toward the center of the body. The balance of the conductive area of the periphery 4-1 is thus equally divided into segmental conductive areas which are of greater circumferential length than the gaps presented by the recesses 43 formed therebetween. This is important insofar as the conductive areas 45 providing a greatest period of contact possible with the brush 23 prior to register of the latter with the next successive gap or non-conductive zone 42.

In FIG. 4 I have shown each recess 45 of rectangular cross section, the width of each recess 43 being slightly greater than the thickness of the brush 28 so that the circuit making period or dwell is greater than the circuit breaking or discharge period. This is exemplified in PEG. 4 to show the conductive zones 15- of more than twice the lineal area than the non-conductive zones or gaps 42. Moreover, FIG. 4 also shows the thickness or commutator contacting surface 47 of the brush 28 as being slightly less than the width of any one recess 43. This is essential to obtaining a complete break of current between the commutator and brush.

In operation the commutator body rotates counterclockwise, FIGS. 2, 3 and 5. The brush 2? remains stationary and has its commutator contacting surface 47 disposed for constant engagement with the periphery 41 of the commutator body 49. As best seen in FIGS. 3 and 4 the brush 28 is of a width comparable to that of the contact making width of the periphery 41 of the commutator body 48. Ordinarily, the spring urged brush 28 would be forced into gap 43 when registered therewith. In accordance with the present invention the brush 28 is secured to an electrically non-conductive rider 50 which rides the periphery 41 of the commutator to maintain the brush in juxtaposition relative thereto. The insulated rider 5% is preferably secured to the back face of the brush as well as to the arm 29 which carries the brush 28. Despite the fact that the arm 29 is spring urged toward the commutator, the rider 50 bears upon the next successive conductive land 45 and thereby supports the brush 28 with its commutator contacting surface 47 in alignment with the periphery of the commutator. Thus it will be seen that the open ended gaps presented by the recesses 43 pass beneath the brush 28 as it is mo- &

mentari'ly supported by the rider resting on the periphery. This is one of the most important features of the present invention as will now be explained.

Now then, as the periphery of the commutator sweeps past the fixed brush 28, the surface 47 of the brush alternately makes and breaks connection relative to the conductive zones 45 of the commutator. As best seen in FIG. 5, irrespective of the speed (r.p .m.) of the commutator 27, there is always a positive circuit making period or dwell which is better than twice as long as the period of discharge effected by contact of the brush with the non-conductive zones 42. This is extremely important because it assures sufficient time for the building up of current in the low voltage side or primary winding 21 of the coil 29. In addition thereto the current so built up in the primary winding 21 is discharged suddenly and quickly into the secondary (high voltage) winding 19 of the coil as soon as the contact surface 47 of the brush is in full register with the gap provided by the recess 43, i.e., a non-conductive zone or gap 42. According to my discovery there is no need to prolong this phase of the operation. As a matter of fact, it is essential that this phase of the operation occur abruptly after the low voltage builds up to its peak in the primary winding of the coil. Thereafter it matters not that the circuit is broken between the battery and the primary side of the coil.

To understand the foregoing phenomenon, consider it analogous to closing of a fluid supply line as the load of the fluid therein builds up to its peak pressure followed by a complete opening of the discharge end of such supply line so that the fluid bursts forth therefrom in a sudden spurt. This, in effect, is comparable to the operation of the make and break arrangement constructed in accordance with the present invention. As a matter of fact, during testing of first experimental models it was discovered that a complete break of contact is essential. in prior known models in which the contact face 47 of the brush bridges the gap between conductive zones 45 a bleeding eifect occurred which caused leakage of the low voltage build-up in the primary winding of the coil. This caused a gradual, rather than a sudden or abrupt "drop in the voltage built up in the primary winding, re-

sulting in a loss of efiiciency in the discharge of the pentup current into the secondary winding of the coil.

From the foregoing experiments, it was found that even the use of a material having high resistance such as carbon for the brush 28, although satisfactory during normal operating or even idling speed of the engine, is not too satisfactory when the engine is being turned over by a starter.

In such a case of slow turning of the commutator 27, it was discovered that during partial contact of a carbon brush 2% with the conductive zone 45 while entering register with a non-conductive zone 42 caused leakage of current from the primary winding into the secondary winding of the coil. Thus it will be seen that a gradual voltage drop would occur prior to firing time, i.e., complete contact of the brush with the zone 4-2, or, to use the analogy of the fluid line explained above, it is as though the discharge end of the pressurized line has been slightly opened prior to complet opening thereof, causing a gradual loss in pressure, thus diminishing the final spurt expected at complete opening of the line.

The foregoing pre drop in voltage built up at slow speed in the primary winding was found to occur only when the brush 28 is made of material such as carbon having a high resistance. It was found that during the slow relative movement of the carbon brush over the non-conductive zone 42 and while only a fraction of the contact surface 47 of the brush is in contact with the conductive surface 45 of the commutator, the resistance of the brush material being only a part of the full surface area 47 was so high that it was like a partial opening of the circuit causing a leakage of the built-up current from the primary winding into the secondary winding prior to firing time. However, when the brush 28 is made of material such as platinum, silver or even steel having a lower resistance than carbon, this leakage does not occur to such a great extent as to cause any appreciable voltage drop in the primary winding. With a brush of such low resistance then, the engine would start upon being turned slowly by the starter.

Having thus explained the workings of the make and break arrangement of the present invention, it will be appreciated that the relationship of the surface area 47 of the brush 28 to the gap 42 be such as to aiford a full clean break in the circuit in order to obtain a sudden drop in the voltage built up in the primary winding 21 of the coil 20. Equally important, however, is the prolonged period of contact between the brush and the conductive land or surface 45 of the commutator to assure a sufiicient surge of low voltage current from the battery 34 into the primary winding of the coil.

While I have described my improved make and break arrangement in specific detail, it will be appreciated that it is susceptible to modification, alteration and variation in structure without departing from the spirit of my invention. I, therefore, desire to avail myself of all modifications, alterations and/ or variations as fairly come within the purview of the appended claims.

What I claim as new and desire to protect by Letters Patent is:

1. In the low voltage phase of the ignition system for an internal combustion engine, the combination with a commutator having a body of electrically conductive material provided with a plurality of empty gaps equally spaced around its periphery and a spring urged periphery engaging brush having a thickness slightly less than the width of any one of said gaps, and an electrically non-conductive means operatively engaging said brush and said commutator for supporting said spring urged brush with its commutator periphery engaging surface in non-contacting peripheral alignment relative to said commutator body as any one gap therein passes said brush.

2. In the low voltage phase of the ignition system for an internal combustion engine, the combination with a commutator having a body of electrically conductive material provided with a plurality of gaps equally spaced around its periphery and a spring urged periphery engaging brush having a thickness slightly less than the Width of any one of said gaps, and an electrically non-conductive rider secured to said brush and disposed to ride upon the periphery of said commutator body for supporting said spring urged brush with its commutator periphery engaging surface in non-contacting peripheral alignment relative to said commutator body as any one gap therein passes said brush,

3. In the low voltage phase of the ignition system for an internal combustion engine, the combination with a commutator having a body of electrically conductive material having a plurality of gaps equally spaced around its periphery to provide a plurality of spaced conductive lands, a periphery engaging brush having a thickness slightly less than the Width of any one of said gaps, means for urging said brush toward the periphery of said commutator, and an electrically non-conductive rider connected to said brush for movement toward said commutator conjointly therewith and adapted to ride upon said conductive lands for supporting said spring urged brush with its commutator periphery engaging surface in non-contacting peripheral alignment relative to said commutator body a any one gap therein passes said brush.

4. In the low voltage phase of the ignition system for an internal combustion engine in which a rotary commutator body having a plurality of gaps on its periphery provides a plurality of electrically conductive lands thereon, a brush of lesser thickness than the width of any one of said gaps, means for yieldably urging said brush toward the periphery of said commutator body, and an electrically non-conductive commutator periphery rider yieldingly movable toward and from said body conjointly with said brush for limiting movement of said brush into any one gap as it passes said brush.

References Cited in the file of this patent UNITED STATES PATENTS 460,109 Burke Sept. 29, 1891 775,933 Parsons Nov. 29, 1904 1,059,134 Fornander Apr. 15, 1913 1,957,152 Severy May 1, 1934 2,204,436 Muzzey June 11, 1940 2,730,582 Jernigan Jan. 10, 1956 2,830,140 Robertson Apr. 8, 1958 2,902,552 De Oliveira Sept. 1, 1959 FOREIGN PATENTS 525,752 Germany May 28, 1931 

